<?xml version="1.0" encoding="utf-8"?>
 <element xmlns="http://relaxng.org/ns/structure/1.0" xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0" name="library">
   <oneOrMore>
     <element name="book">
       <attribute name="id"/>
       <optional>
         <attribute name="available" a:defaultValue="true">
           <choice>
             <value>true</value>
             <value>false</value>
           </choice>
         </attribute>
       </optional>
       <element name="isbn">
         <text/>
       </element>
       <element name="title">
         <attribute name="xml:lang"/>
         <text/>
       </element>
       <zeroOrMore>
         <element name="author">
           <attribute name="id"/>
           <element name="name">
             <text/>
           </element>
           <element name="born">
             <text/>
           </element>
           <optional>
             <element name="dead">
               <text/>
             </element>
           </optional>
         </element>
       </zeroOrMore>
       <zeroOrMore>
         <element name="character">
           <attribute name="id"/>
           <element name="name">
             <text/>
           </element>
           <element name="born">
             <text/>
           </element>
           <element name="qualification">
             <text/>
           </element>
         </element>
       </zeroOrMore>
     </element>
   </oneOrMore>
 </element>
